Sony SSC-C104 Manual de serviço - Página 11

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when the reference chart is exposed. To reduce color

inconsistency in high luminance, when G exceeds a

certain value, the RGB are set so that they settle at the

same level, using the highlight mask circuit which is

composed of Q405, Q406, Q407, and IC401.

Luminance signal processing (IC403 CXA1391/IC801

CXA1592)

Taking into consideration the delay generated by

chroma matrix processing, the luminance signal is

passed through FL401 and FL402 to adjust the delay

amount and input to pin 64 of IC403. The Y signal

which has been gamma corrected is output from pin 5,

passed through the delay line FL801 for adjusting the

Y/C phase, and input to pin 35 of IC801.

Encoder (IC801, CKA1592)

The color difference signals (R-Y, B-Y) output from

IC403 are each input to pins | and 47 of IC801. These

are added with the modulated color difference signals

and output from pin 16 of IC801, then passed through

the band pass filter, and returned to pin 18 again. Next,

they are mixed with the luminance signal and output

from pin 21 as the composite signal. The luminance

signal is added with the H aperture correction signal

(pin 33) and V aperture correction signal (pin 42), and

added with the sync signal.

The H aperture signal is level-adjusted by the voltage

of pin 36 of IC801. After the noise slice level is

regulated, it is added to the luminance signal. By

linking the level adjustment voltage to AGC, when

AGC

rises during low luminance,

the aperture

correction amount is dropped to decrease the noise.

The V aperture signal is passed through FL802 where

its phase is adjusted to the Y signal, and then input to

pin 42 of IC801.

SSC-C104/C108P

3-3.

AC-172 Board, VCA-6 Board

(SSC-C108P only)

These boards compose the power supply block. A sub-

board VCA-6 is mounted on the main AC-172 board. The

RCC PWM

control method is adopted as the circuit

method.

The commercial-use power supply input through the noise

filter composed of the capacitor and line filter is rectified by

D401, and input to the switching transformer T401. The

PWM control IC (IC401) drives the switching FET (Q401)

to perform power transmission. The oscillation frequency

of this control IC is regulated to 100 KHz by the capacitor

of pin 7. The voltage is extracted from the Q401 source via

R412 and R413 to impose over-current protection. The

snubber circuit composed

of D403, R408, and C412

controls the switching surge voltage to below 450V.

The secondary side output power transmitted takes SV as its

reference. It is compared with the reference value of the

1C504 shunt regulator of the VCA-6 board.

If higher than the prescribed voltage, current is sent to the

photo coupler PH401 in high volume to decrease the IC402

comparator voltage and shorten the ON time.

The reference value of the shunt regulator IC501 is adjusted

by VRS501 of the VCA-6 board so that the prescribed

voltage value can be set.

The 5V output passed through the ripple filters C420 to

C425 and L401 is raised to 9V, 15V, and -8.5V in the step-

up circuit by the PWM method by IC503 (TL1451) of the

VCA-6 board, and supplied to the main board. The forced

start up circuit composed of IC501 is incorporated here to

raise the reliability of the power supply.

3-4.

IR-17 Board

This board serves as the signal switching relay board of the

auto iris lens.

The output signal is switched to the DC servo or VS servo

by SWI.